Interpretive Summary: Fundamental knowledge on poultry immune system and the parasite antigens that host receptors interact with is needed to develop a logical control strategy against avian coccidiosis. In this paper, ARS scientist collaborated with a scientist at the University of Zaragusa in Spain to identify new membrance protein, flotillin which is important in mediating cell invasion of parasites into host cells. Flotillin-1, a resident protein of lipid rafts, was prominently expressed at the apex of the cells, a region mediating host invasion and the pretreatment of sporozoites with antibody against flotillin-1 blocked parasite invasion. These results will be used to develop a new control strategy against avian coccidiosis.

Technical Abstract:
Lipid rafts are detergent-resistant, liquid-ordered microdomains in plasma membranes that are enriched in cholesterol and sphingolipids and involved in intracellular signal transduction, membrane trafficking, and molecular sorting. In this study, we investigated the possibility that lipid rafts on Eimeria tenella sporozoites may act as platforms for host cell invasion. Flotillin-1, a resident protein of lipid rafts, was identified on E. tenella sporozoites and was prominently expressed at the apex of the cells, a region mediating host invasion. Pretreatment of sporozoites with antibody against flotillin-1 blocked parasite invasion. Furthermore, the anti-coccidial drug monensin disrupted the localization of flotillin-1 within raft structures resulting in loss of invasion. We conclude that Eimeria sporozoites utilize lipid rafts containing flotillin-1 for internalization into host cells.